Radio frequency amplifying and modulating devices



July 13, 1965 E. E. sTElNBREcl-IER 3,195,072

RADIO FREQUENCY AMPLIFYING AND MODULATING DEVICES Filed Jan. 25, 1960 3 Sheets-Sheet 1 RJ? /N RE OUT (A MPL H7517) F/G. /a

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F/ G. 2 Y ELECTRO 60N uws/v rol?, ERNST E srE//vafcHm A T TOR/VE Y July 13, 1965 E. E. STEINBRECHER RADIO FREQUENCY AMPLIFYING AND MODULATING DEVICES Filed Jan. 25. 1960 PIECE JZ MA rnv/Na 3 Sheets-Sheet 2 JOWN WARDS TRA VEL ING @Low msc/Afef f 'fou/VD WAVES WA VES SHOCK WA V55' /NvE/vron,

ERNST 5. srE/NRfCHEH ATTORNEY July 13, 1965 E. E. STEINBRECHER 3,195,072

RADIO FREQUENCY AMPLIFYING AND MODULATING DEVICES F-led Jan. 25. 1960 3 Sheets-Sheet 3 VIBRA T10/V VA L V5 22 @MMA rok ELECTRO/VHEIM.

.SHOCK WA V55 ELECTRO/V GUN .SOUND 0R .SHOCK ATTORNEY United States Patent O 3,195,072 RADIO FREQUENCY ABWLHTYHNG AND MQDULATHNG DEWCES Ernst E. Steinbreeher, 57 Essex Ave., Montclair, NJ. Filed lan. 2S, 196i), Ser. No. 4,369 23 Claims. (Cl. S32- 7) This invention relates to radio frequency amplifying and generating tubes.

This invention relates to radio frequency amplifying and generating tubes, and more specifically to tubes of the travelling wave type or other electronic discharge devices using electron bunching to control an electronic discharge path.

It is known in the art of designing microwave tubes, that in a certain group of these tubes, for instance, in travelling wave tubes, backward wave oscillators and also in some magnetrons, a periodical structure is used for iniluencing the electr-ons in 4a .specific manner. By means of this structure the electrons of an electron beam, which passes close to the structure, are hunched together by changing the velocity of the electrons or the cross-section of the whole electron beam.

Due to this interaction between the electron beam and the periodical structure more and more of the direct current energy in the originally unmodulated beam, is changed into radio frequency energy.

There exist two types of such periodical structures. One is a wire helix in the center of which the electron beam travels; the other is a periodic structure electrically behaving as a filter and mechanically appearing as a series of teeth or discs on a support member (FIGS. la, b, c). While both structures may be used for amplification as well as oscillation, the helix is generally used for amplification, the teeth structure for oscillation.

La extending tubes of this design to higher frequency and higher power, these mechanical structures impose severe limitations. In order to increase the frequency, the physical dimensions of this structure must be made smaller and smaller until the limit of the manufacturing skill is reached. To increase the power, the electron beam must be made denser and denser because only the electrons close to the surface of the structure will interact suiciently. The size of the structure also limits power because stray electrons will hit it and heat it up.

In the case of small dimensions, these structures will easily reach the point of destruction.

One of the objects of the invention, therefore, is to overcome these shortcomings.

ionized gases have been found in may cases to exhibit electric properties similar to those of conductors. For instance they conduct an electric current and reflect electromagnetic waves. On the other hand they exhibit propertics which might be desirable in the case of influencing an electron beam: they are penetrable by electrons, which permit to inliuence a beam with large cross-section, a task which is very diiiicult to perform with mechanical structures in this particular application.

It is evident from the basic theory of these tubes that the essential part of them is the periodic structure.

It is therefore another object of the invention to provide a periodic structure for electron passage in the form of a gas inhomogeneously distributed over the electron path for example by means of the application thereto of sound waves propagated or standing, or by means of shock waves, or by mixtures of such waves.

A further object of the invention is to pass electrons through mechanical waves produced in a gas so as to cause in alternating areas of higher and lower gas density or pressure, electron-bunching under control of the waves,

A further object of the invention is to provide along an electron path, a gas discharge excited by a modulated ice radio frequency wave, and to derive from the electron path an amplified output corresponding to the radio frequency modulation input.

A more specific object of the invention is to produce mechanical standing waves along an electron discharge path, to modulate these Waves with an input signal and to derive from the electrons an output signal.

Still another object of the invention is to produce signal modulated shock waves in a gaseous medium extending through an electron discharge path and to derive from the electron bunching occurring at points of different gas densities or pressures along the path, an output varying with the modulation.

These and other objects of the invention will be more fully apparent from the drawings enclosed herewith in which FIGS. la, b, and c represent existing types of electronic discharge tubes using electron bunching.

FIG. 2 shows an electronic discharge tube embodying certain principles of the invention.

FIGS. 3 to 9 represent modications of the invention such as shown in FIG. 2.

As shown in FIG. 2 an electronic tube using this principle may have the following basic layout.

An electron gun 1 of more or less conventional design directs an electron beam from one side into a gas lled container or tube 2. On the other side of tube 2 an electro-accoustical transducer 3, also of well known structure is mounted, which radiates sound or sho-ck waves into tube 2. The electrons now have to pass through areas of higher and lower gas pressure which will create the desired interaction with the electrons in the form of amplification of a signal fed into one end and taken out on the -other end of tube 2.

For coupling and decoupling of energy on the electron beam, helicoidal coils or similar devices are used such as shown at 4, 5. Around tube Z, a wave guide 6 is mounted, depending on the type of generation mechanism used. A focusing coil wound around tube 2 serves to concentrate electron beam 8.

The transducer 3, controlled by generator 3' for generating the sound or shock Wave, required in accordance with the invention, may be of varying design depending on the type of waves we expect. Since the gas pressures required has been found to be very low, ordinary transducer means such as loudspeakers or ceramic transducers of standard application may not be ecient enough.

For these reasons, in accordance with a preferred ernbodirnent of the invention, gas discharge devices are used.

More specilically, for sinusoidal excitation, an arrangement such as shown in FIG. 3 is provided.

In this case between t-wo electrodes 9, lll a gas discharge will be excited in vessel il by a radio frequency generator 12 which is modulated with an audio or hyperaudio frequency derived from ampliiier 13.

A glow discharge produced in vessel 1i will then expand and contract under control of the audio modulated radio frequency, acting like a gas loudspeaker used in certain audio applications.

Discharge vessel lll is connected over a matching piece 14 to propagation tube l5 to insure the highest pressure changes obtainable in this arrangement.

In order to increase this effect, in accordance with the invention, standing waves are created in propagation tube 1S.

In a further embodiment of the invention, intensity changes in the gas are produced by means of a shock wave. While in the case of sound Waves, the molecules of the gas -oscillate around a mean position and are not transported along the tube, a shock wave involves a physical movement of the gases from one area into others.

ln order to generate shock waves at low gas pressure,

in accordance with the invention, high density spark discharges or magnetic discharges are used.

In FIG. 4, a capacitor 16 is shown to be charged by power supply 17 and discharged by means of a trigger device 18, thereby creating shock waves which are luminescent and consequently ionized, and which will travel along propagation tube 15.

A similar varrangement is shown in FIG. where a magnetic shock discharge is produced by discharge ca- Y pacitor 16 and trigger 18 connected to a coil 19 surrounding gas tube 20.

FIG. 6 indicates an electromechanical transducer in the form of a vibratable needle valve 21 which closes a gas reservoir 22 off from the main tube 23, and which is opened and closed rhythmically by electromechanical transducer 24 driven from a generator Z5, thereby admitting gas bursts into tube 23.

A vacuum pump 24 serves to maintain vessel 23 at a predeterminedly low gas pressure.

While FIG. 2 shows a transducer 3 mounted on the opposite side with respect to electron gun l, FlG. 7 illustrates feeding sound or shock wave in the direction of the electron movement and FlG. 8 shows a feed in opposite direction. Because of Vthe great difference in speed of the electrons (around l()9 cm./s.) as compared to that of sound and shock waves (101-105 cm./s.) the latter can be considered in the rst approximation as not moving relative to the electrons.

Other modications of the invention will be apparent from the following considerations.

Traveling wave tubes are based on linfluencing an electron beam along the whole length of its llow. This is in contrast to more conventional tubes, where the interaction takes place in a certain givenV small area. ln orderto accomplish this purpose the velocity of an electro-magnetic wave is slowed down to the speed of the electron beam. The slow propagating field now interacts more efhciently with the electrons of the beam because they have-so to speakmore time to do so.

In traveling wave tubes as already mentioned above, originally the field was slowed down by means of a helicoidal conductor which forces the iield to flow around the windings and thus slows down the propagation speed along the axis. The electron beam therefore has to be aimed in the direction of the axes of the helix.

In applying this principle to the invention, other slow wave structures' may be used without departing from the scope of this disclosure.

More specifically, such slow wave structures maybe formed by delay lines representing substantially lters consisting of numerous elements. Operated close to the cut off frequency, each of these elements will have a considerable phase angle which is similar to the propagation of the field around one turn of the helix type conductor mentioned above. While in the technique of lower frequencies such a delay line is made of coils and condensors, in the centimeter and millimeter wave range such filters or delay lines are constructed as transmission elements such as shown in FIG. lb and'FlG. 1c. The electron beamy can be readily focused along these lines in the manner indicated in these figures. i Y

In this configuration, and in accordance with another aspect of the invention, a more specific system may be used.

in accordance with the principles set forth above the wave traveling along the delay line must not have the same velocity as the electron beam but can Vtravel faster as long as the phase conditions are favorable in the interaction gaps (FIG. lc) to enhance the bunching of the electron beam. Since, at least in principle, there is no difference which wave fronts are interacting, the waves along the structure can be made to travel much faster in the areas of no interaction. By proper arrangements of both these areas, in accordance withpanother feature of the invention, amplification and/ or oscillation is achieved evenv if the two waves are propagating in opposite directions. Y Y

In this connection, and as 5a further embodiment of the invention, the gaps need not be excited by a propagating wave.

For example as shown in FIG. y9 an appropriate array of successive voltage gaps shown at 25 to 30 and connected alternatively to the plus and minus electrodes of a power source (not shown) has beenfound sufficient to produce the varying gas densities along the electron path and to excite waves along an electron beam 3l.

' It is quite clear that the invention is notlimited to the arrangements and methods shown or described.

VIn accordance with the invention, along any gas structure which is capable of influencing an electron beam, anoscillation can be excited or a signal can be amplified as long as certain operatingconditions are maintained.

In the case where the periodic structure consists of a gas with different densities, the advantages of such a structure against a mechanical structure are as follows: (l) The structure can be penetrated by electrons therefore allowing the interaction with more electrons without increasing the beam density.

(2) The structure-.is made out of gas molecules and therefore not subjected to limitation inherent in the designing and machining of mechanical structures.

(3) The structure can be easily changed from the outside of the tube by changing the excitation conditions (frequency, etc.) which will increase the frequency range of such a tube, because the frequency range is determined mainly by the periodicity of this structure, and morer particularly by the distance of interaction areas.

While the invention hasy been described and illustrated by way of various mechanical and electromechanical elements, and assembly of elements, the invention is not limited thereto, but may be applied in any form` or manner whatsoever without departing from the scope of this disclosure.

I claim:

In an electronic discharge device, means for directing electrons alonga predetermined path, input means for applying a modulating signal to said electrons, means for producing" mechanical waves of a frequency substantially below the frequency range of said Vmodulating signal, means including a gas extendingV along said path, for applying said'waves to said gas to produce along said path a. predetermined sequence of points of minimum and maximum gas pressure causing said gas to be hunched at said points, and means for deriving from said electrons an output signal.

2. Device according to claim 1 wherein continuous mechanical waves are produced.

3. Device according to claim l wherein mechanical standing waves are produced.V i

d. Device according to claim l wherein mechanical shock waves are produced.

5. Device according to claim l wherein both mechanical shock waves and continuous waves are produced. i

@.Device Iaccording to claim 1 wherein said wave producing means include an electromechanical transducer arranged at one end of the electron path; saidy electron directing means being 'arranged at an opposite end.

7. Device according to claim l wherein said wave producing means include an electromechanical transducer arranged at one end of said electron path; said electron direct-ing means being arranged 'at the same end.

8. Device `according to claim ll comprising a tube containing said electron path, and wherein said wave producing means include glow discharge means and a signal modulated radio frequency generator controlling said gas discharge mean-s; said gas discharge means being arranged at one end of said tube communicating therewith; the

eriodic encadre other end of said tube being closed to permit rellection of the waves.

9. Device according to claim 1 comprising a tube containing said electron path, and wherein said wave 4producing means include gas discharge means, triggering means controlling said gas discharge means, a discharge capacitor controlling said trigger means and a charging power supply controlling said capacitor; said gas discharge means being arranged at one end of said tube communicating therewith; the other end of said tube being closed to rellect the waves.

19. Device according to clairn 1 wherein said wave producing means include magnetic discharge winding means surrounding said path, triggering means controlling said winding means, a discharge capacitor controlling rsaid triggering means, and Ia charging power supply controlling said capacitor.

11. Device according to claim 1 comprising a tube containing said electron path, and wherein said wave producing means include magnetic discharge winding means surrounding said path, triggering means controlling said winding means, a discharge capacitor controlling said triggering means, and a charging power supply controlling said capacitor; said tube being closed at opposite ends and said winding means being varranged ata point intermediate said ends.

12. Device according to claim 1 comprising a tube containing said electron path, and wherein said wave producing means include a gas reservoir in communication with said tube, and a vibratile valve arranged in the path of communication between said gas reservoir and said tube, a source of modulated wave power, means for vibrating said valve under control of said power source to produce shock waves in said tube.

13. Device according to claim 1 wherein said tube is connected at one end to said gas reservoir and a vacuum pump is connected to the tube at its other end.

24. Device according to claim 1 comprising a tube containing said electron path; said electron directing means and said wave 'applying means being arranged at one end of the tube but on separate branches thereof.

15. Device according to claim 1 comprising a tube containing said electron path; said electron directing means and said Wave applying means being `arranged at one end or" the tube but on separate branches thereof; the other end of said tube being closed.

16. Device according to claim 1 comprising a tube containing said electron path; said electron directing means and said wave applying means being arranged at opposite ends of lsaid tube; said tube at least at one of said ends forming a separate branch closed at said end.

17. Device according to claim 1 wherein said wave applying means include a number of spark gaps arranged along said path of electrons7 each spark gap including a pair or opposite electrodes; and means for applying voltages of opposite polarities to successive pairs of electrodes.

l, In an electronic discharge device, means for directing electron along a predetermined path, input means for applying a modulating signal to said electron, a gas extending along said path, electroacoustic transducing means under control of a predetermined frequency substantially below the frequency range of ysaid modulating signal for varying the density of said gas |along said path to produce alternating areas of high and low gas densities thereby causing said gas to be hunched at predetermined points of said path, and means for deriving output from said path.

19. Device laccording to claim 13 wherein said density varying means include means for producing a gas discharge in said gas.

2t?. Device according to claim 1g wherein said density varying means include means for applying sound waves to said gas.

21. Device according to claim 18 wherein said density varying means include means for applying shock waves to said gas.

22. Device according to claim 18 wherein said density varying means include electro-mechanical transducer means.

23. Device according to claim 18 wherein said density varying means include electrode means arranged along the electron path and controlled by alternating Voltage polarities.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN AN ELECTRONIC DISCHARGE DEVICE, MEANS FOR DIRECTING ELECTRONS ALONG A PREDETERMINED PATH, INPUT MEANS FOR APPLYING A MODULATING SIGNAL TO SAID ELECTRONS, MEANS FOR PRODUCING MECHANICAL WAVES OF A FREQUENCY SUBSTANTIALLY BELOW THE FREQUENCY RANGE OF SAID MODULATING SIGNAL, MEANS INCLUDING A GAS EXTENDING ALONG SAID PATH FOR APPLYING SAID WAVES TO SAID GAS TO PRODUCE ALONG SAID PATH A PREDETERMINED SEQUENCE OF POINTS OF MINIMUM AND MAXIMUM GAS PRESSURE CAUSING SAID GAS TO BE BUNCHE AT SAID POINTS, AND MEANS FOR DERIVING FROM SAID ELECTRONS AN OUTPUT SIGNAL. 